不同冷却方式对热轧带钢氧化皮结构及其耐蚀性的影响

利用不同冷却方式在SS400热轧带钢表面形成了不同结构的氧化皮,通过腐蚀形貌宏观观察、SEM、EDS、XRD、失重法、干湿周期浸润腐蚀加速实验和电化学方法对不同结构氧化皮的热轧带钢在NaHSO₃溶液中腐蚀行为进行了研究。研究表明,不同冷却方式下所制热轧带钢的氧化皮均主要由Fe₃O₄组成,另含有Fe₂O₃和Fe。随着冷却速度的减小,氧化皮中Fe₃O₄的含量增加,但未发现有FeO;随炉冷却所制热轧带钢的氧化皮较厚且均匀,并存在分层现象(外层为Fe₂O₃,内层为Fe₃O₄+Fe),在NaHSO₃溶液中耐蚀性最好;装罐冷却所制氧化皮较均匀平整,耐蚀性次之;自然空冷所制氧化皮存在着较多的缺陷,耐蚀性最差。     

X80管线钢钝化膜在各种高浓度NaHCO3溶液中的电化学行为

采用动电位极化曲线、恒电位极化曲线、电化学阻抗谱(EIS)、Mott-Schottky分析等电化学方法研究了X80管线钢在各种高浓度的NaHCO₃溶液中形成钝化膜的电化学行为。结果表明, X80管线钢钝化膜的稳定性和耐蚀性会受到NaHCO₃溶液浓度的影响。钝化膜电化学性质随HCO₃^-浓度升高而降低;内层Fe₃O₄的厚度不随HCO₃^-浓度变化,推测其形成与成膜电位有关;内外膜层厚度比随HCO₃^-浓度的升高而增大,钝化膜的稳定性和耐蚀性主要受外层γ-Fe₂O₃的影响。根据点缺陷(PDM)理论的分析认为,NaHCO₃溶液浓度升高时钝化膜稳定性和耐蚀性的降低与溶液电导率的升高和HCO₃^-在缺陷点处吸附作用的增强有关。     

H2S/CO2环境中L360钢点蚀行为研究

利用静态挂片失重法研究了含H₂S/CO₂模拟油田水溶液中, 温度及Cl^-浓度对L360管线钢点蚀的影响, 并利用Gumbel第一类近似函数分析了最深蚀孔概率. 结果表明, 在40℃~70℃之间, Cl^-浓度为10 g/L条件下, 点蚀的严重程度随温度增高而增大. 恒定温度下, Cl^-浓度对点蚀发生也有明显的影响, 当Cl^-在10×15 g/L范围时, 腐蚀试样发生明显的点蚀; 当Cl^-浓度大于20 g/L时, 试样主要发生均匀腐蚀, 随着Cl^-浓度的增大, 腐蚀产物膜变得更加疏松, 保护性能下降, 均匀腐蚀速率增大. 最深点蚀分布服从Gumbel第一类近似函数.     

超级双相不锈铸钢电化学极化表面腐蚀产物的XPS分析

采用X射线光电子能谱(XPS)技术研究了超级双相不锈铸钢在人工海水中经电化学极化后表面腐蚀产物。结果表明：双相不锈钢在人工海水中极化后的钝化膜表层主要以CrO₃、CrOOH、Cr(OH)₃和Fe(OH)₃等氢氧型化合物为主,内层主要以CrO₃、Cr₂O₃、FeO和Ni₂O₃等氧化物为主,同时膜内层存在Fe、Cr、Ni和Mo单质。MoO₄^2-和NH₄⁺吸附在钝化膜表面,对钝化膜起到保护作用。     

(Y,Gd)2O3:Eu3+纳米粒子制备过程中的合成动力学

采用反向滴定共沉淀法制备出（Y,Gd）₂O₃:Eu³⁺前躯体,再在不同温度下煅烧,获得（Y,Gd）₂O₃:Eu³⁺纳米粒子,用XRD和SEM对样品物相组成及形貌进行了表征;用TG-DTA获得了佯品在不同升温速率下的热分解曲线.结果表明,前躯体在煅烧过程中的物相变化分为3个阶段,用Doyle-Ozawa法和Kissinger法分别计算出各个反应阶段的表观活化能,其平均值分别为191.54,557.05和236.58 kJ·mol^-1并建立了动力学方程;（Y,Gd）₂O₃:Eu³⁺晶粒生长活化能是35.58 kJ.mol^-1,纳米粒子形核过程中的晶粒长大由晶界扩散控制.     

红壤中变电站接地网金属材料的腐蚀行为分析

采用扫描电镜 (SEM)、能谱 (EDS) 和X 射线衍射 (XRD) 等技术对红壤中变电站接地网服役长达13 a的镀锌扁钢进行了形貌分析和腐蚀产物分析。结果表明,该镀锌扁钢受到严重腐蚀,腐蚀产物主要由FeOOH,Fe₃O₄和Fe₂O₃等组成,腐蚀产物分层的原因是新生成的腐蚀产物沉积在金属/腐蚀产物层界面或腐蚀产物开裂处,同时S和Cl对内层腐蚀产物具有较大的影响。Tafel测试结果表明,在腐蚀电流峰值附近,SO₄^2-与Cl^-的百分比为1∶2时,两者对镀锌Q235碳钢在该红壤中的腐蚀性影响具有等效作用。通过室内加速实验模拟镀锌Q235碳钢在该红壤中的腐蚀发现,镀锌Q235碳钢的腐蚀速率呈现先增大后减小的规律,该加速实验在未改变镀锌Q235碳钢腐蚀机理的同时具有较好的加速效果。     

核电站蒸汽发生器传热管用Inconel合金在高温高压水中的腐蚀行为研究

研究了核电站蒸汽发生器传热管用合金材料在模拟压水堆一回路水环境中形成的腐蚀氧化膜,首次获得了原位振动光谱。Inconel 600合金的拉曼谱中存在3个峰,540 和610 cm^-1拉曼峰源自于表面生成的Cr₂O₃氧化膜,670 cm^-1峰对应于表面生成的FeCr₂O₄尖晶石产物,随着电位的增加,670 cm^-1峰的相对强度显著增强。Inconel 690合金的表面氧化膜由Cr₂O₃构成,不含NiO或尖晶石成份。Inconel 600合金发生应力腐蚀开裂 (SCC) 的敏感性与其表面氧化膜的变化存在关联性。Inconel 690合金尚未发现SCC现象,这与其表面生成的稳定的氧化膜有关。     

On rubidium lanthanide double chromates

Synthesis and crystallographic data are reported for a family of double rubidium-rare earth chromates RbLn(CrO₄)₂, where LnLa---Lu, Y and Sc. The compounds are closely related to the potassium chromates KLn(CrO₄)₂ but with a slightly different distribution of structural types: those of La, Pr and Nd are monoclinic, Sm, Eu, Gd are orthorhombic and those of Tb-Lu are also monoclinic but with another unit cell. RbSc(CrO₄)₂ has high and low temperature forms: hexagonal and monoclinic respectively. Lattice parameters of all the above compounds are given. Thermal decomposition takes place over 450 °C leading to the rare earth chromites and Cr₂O₃.     

Spectroscopic and 1.06 μm laser properties of Nd-doped K–Sr–Al phosphate and fluorophosphate glasses

Optical absorption, fluorescence and decay curves for the ⁴F_3/2 level of Nd³⁺ ions in phosphate (P₂O₅–K₂O–SrO–Al₂O₃) and fluorophosphate (P₂O₅–K₂O–SrO–Al₂O₃–AlF₃ and P₂O₅–K₂O–SrO–Al₂O₃–BaF₂) glasses doped with three concentrations (0.1, 1.0 and 2.0 mol%) of Nd³⁺ ions have been investigated. The Judd–Ofelt (JO) theory has been applied to the absorption spectra of 1.0 mol% Nd³⁺-doped glasses to derive JO intensity parameters which are in turn used to calculate the radiative properties of the Nd³⁺ ion fluorescent levels. The assigned energy level data of Nd³⁺ (4f³) ions are analysed in terms of a parametrized free-ion Hamiltonian model that consists of 20 interaction parameters of atomic nature. The stimulated emission cross section and branching ratios have been calculated using the emission spectra. The relatively higher branching ratio for ⁴F_3/2 → ⁴I_11/2 transition shows the suitability of these glasses for laser application. It is interesting to note that the measured decay curves of the ⁴F_3/2 level remain nearly single exponential even for higher Nd³⁺ ion concentration but with shortening of lifetime.     

覆有短期腐蚀产物膜的X80钢的电化学行为

将X80钢放入酸性鹰潭土壤模拟溶液中浸泡30 d使其表面形成短期腐蚀产物膜,采用SEM,EDS和XRD对腐蚀产物膜的表面形貌、元素和物相组成进行测试与分析,通过极化曲线和电化学阻抗方法考察腐蚀产物膜对X80钢电化学腐蚀行为的影响。结果表明：与X80裸钢相比,腐蚀产物膜作用下的X80钢的自腐蚀电位更负,自腐蚀电流密度更大。这是因为产物膜主要由Fe₃O₄和β-FeOOH组成,短期形成的Fe₃O₄产物膜存在很多微小孔洞和微裂纹等缺陷,为溶液中侵蚀性Cl^-的吸附和滞留提供了潜在场所,同时也增大了基体和腐蚀介质反应的有效面积;而产物膜中的β-FeOOH抗Cl^-侵蚀作用很弱,且参与了阴极还原反应。这些因素的综合作用导致覆有短期腐蚀产物膜的X80钢在酸性土壤模拟溶液中表现出更大的腐蚀速率。     

O3/Cl-复合大气环境中Q235B钢的腐蚀演化特性

采用干/湿交替的实验方法模拟大气腐蚀过程。运用X射线衍射、电化学阻抗谱以及极化曲线等手段，研究了O₃/Cl^-复合大气环境中Q235B钢的腐蚀演化特性。结果表明，O₃和Cl^-的协同作用对Q235B钢的腐蚀有明显的促进作用，其腐蚀速率随着模拟环境中Cl^-含量的增加而增大。腐蚀演化特性方面，Q235B钢在腐蚀的初期阶段腐蚀速率最大，中期阶段腐蚀速率迅速下降，而到后期阶段腐蚀速率又有所提高。相比于不含O₃的大气环境，当Cl^-浓度较低时，O₃和Cl^-对Q235B钢腐蚀产物组份的影响并不明显。而当Cl^-浓度较高时，O₃和Cl^-能明显促进β-FeOOH的生成而抑制α-FeOOH和γ-FeOOH的生成。这说明O₃/Cl^-复合大气环境能促进Q235B钢的大气腐蚀与锈层相组分变化密切相关。     

Effects of H2O2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

The effects of H₂O₂ pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA) were investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF) soaking test. It is found that the H₂O₂ pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni₂O₃, Na₂TiO₃ and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment. As a result, the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na⁺ ions from Na₂TiO₃ phase with H₃O⁺ ions in SBF, which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H₂O₂ pretreatment.     

温度对X70钢在高pH值溶液中腐蚀行为的影响

采用动电位极化、电化学阻抗谱技术、Mott-Schottky等测试方法,研究了温度对X70钢在高pH值溶液 (0.5 mol/L Na₂CO₃+0.5 mol/L NaHCO₃) 中钝化膜性能和电化学腐蚀行为的影响。结果表明：随着温度升高,X70管线钢的点蚀电位降低,维钝电流密度和钝化膜的极化电阻减小。在实验温度范围内,钝化膜为Fe₂O₃和Fe₃O₄的混合物,半导体类型为n型半导体,且不随温度升高而改变。但是随着温度的升高,钝化膜缺陷密度增加,膜厚度减小,腐蚀倾向增大。因此,温度升高会降低钝化膜的稳定性,导致其保护作用下降。     

Fracture toughness of sintered Mo–La2O3 alloy and the toughening mechanism

The K_IC of sintered Mo–La₂O₃ alloy and pure molybdenum was tested and the micro-structure was investigated by SEM, TEM and AES. The results show that the K_IC of Mo–La₂O₃ alloy reaches 24.76 MPa m^1/2, which is 2.5 times as much as that of pure Mo. The sintered Mo–La₂O₃ alloy and pure molybdenum have similar equiaxed grain structure. The AES analysis revealed that the same content of interstitial impurities exist on grain boundaries of Mo–La₂O₃ alloy and pure molybdenum. A toughening mechanism was proposed to be that large number of dislocations were pinned around La₂O₃ particles, shortening the efficient slip length and decreasing the dislocation pile-up on grain boundaries of Mo. The improvement of toughness of Mo–La₂O₃ alloy was attributed to the relief of stress concentration at the grain boundaries of Mo–La₂O₃ alloy and the weaker tendency to intergranular fracture on grain boundaries.     

铁素体-马氏体钢P91和P92在超临界水中腐蚀后氧化膜多孔性分析

用X射线衍射（XRD）和扫描电镜-电子能谱（SEM-EDX）技术研究P91、 P92在500℃/25 MPa和550℃/25 MPa超临界水中腐蚀后氧化膜的多孔性成因。结果表明,两种材料氧化膜均为双层结构,外层氧化膜为 Fe₃O₄相,内层氧化膜为Fe₃O₄和FeCr₂O₄相,P92在接近氧化膜区域的基体内存在一个内氧化区。P91和P92在超临界环境中腐蚀后氧化膜的多孔性与外层氧化膜Fe₃O₄的缺陷类型有关,富氧Fe₃O₄中的缺陷主要类型为氧空位,在超临界状态下,当氧空位浓度达到一定程度后,空位坍塌即形成小孔。     

再生水消毒对循环冷却水系统的腐蚀速率研究

无机消毒剂ClO₂和有机消毒剂季铵盐 (苯扎溴铵) 作为常用的再生水消毒剂对循环冷却水系统具有一定的腐蚀性。通过两种消毒剂的对比,发现消毒后残留的Cl^-和氨氮分别是两种消毒剂对316L不锈钢产生腐蚀的主要因素。此外,采用响应面分析法 (RSM) 和中心组合设计 (CCD) 分析了温度和流速对316L不锈钢腐蚀速率的作用。结果表明,在低温和低流速的情况下,瞬时腐蚀速率变化较小,产生腐蚀的主要原因还是电化学腐蚀。     

Structure and electrochemical properties of Li(Ni0.5Mn0.5)1-xTixO2 prepared by one-step solid state reaction

The layered compound Li(Ni_0.5Mn_0.5)_1-xTi_xO₂ powders were prepared with Ni(OH)₂, MnCO₃, Li₂CO₃ and TiO₂ by one-step solid state reaction. The effect of doping Ti on the structure and electrochemical properties was studied. The XRD results indicate that the powders with 0≤x≤0.05 have good layered structure and trace of impurity appears in the samples with x≥0.1. The SEM photographs show that the particle size distributes homogeneously and the sample with x=0.15 has larger particle size than other samples. The charge-discharge tests show that Li(Ni_0.5Mn_0.5)_0.95Ti_0.05O₂ synthesized at 800 °C for 36 h exhibits good electrochemical properties. It firstly delivers 173 mA·h/g and maintains 90% of the initial discharge capacity after 30 cycles. The cyclic voltammetry and differential capacity vs voltage curves show that the major oxidation and reduction peaks are around 3.95 V and 3.75 V, respectively, assigned to Ni²⁺/Ni⁴⁺ oxidation-reduction process. A weak peak around 4.5 V is found during the oxidation process in the first cycle, which can be regarded as the main reason of the large drop of discharge capacity in the initial cycle.     

Processing, microstructure, and properties of laser remelted Al2O3/Y3Al5O12（YAG） eutectic in situ composite

Laser remelting and rapid solidification were performed in preparing the high-performance Al2O3/Y3Al5O12（YAG） eutectic in situ composite. The microstructure characteristic and solidification behavior were studied using scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）, X-ray diffractometry（XRD） and simultaneous thermal analysis（STA）. The hardness and fracture toughness were obtained using an indentation technique. The results show that the laser remelted Al2O3/YAG composite has a homogeneous eutectic microstructure without microcrack and pore. The component phases of Al2O3 and YAG are three-dimensionally and continuously reticular connected, and finely coupled without grain boundaries, colonies and amorphous phases between interfaces. The eutectic interspacing is greatly refined with increasing the scanning rate and average is only l μm. The synthetically thermal analysis indicates that the eutectic temperature of Al2O3-YAG is 1 824 ℃, well matching the phase diagram of Al2O3-Y2O3 system. The maximum hardness reaches 19.5 GPa and the room fracture toughness is 3.6 MPa.m^1/2.     

Cr、V合金化弹簧钢腐蚀产物的相组成与转化

采用中性盐雾腐蚀实验对不同Cr与V含量的合金弹簧钢进行了24~288 h的腐蚀实验，用光学显微镜(OM) 观察腐蚀样品的表面宏观形貌，通过扫描电镜 (SEM) 观察腐蚀产物 (简称锈层) 截面情况，用能谱仪(EDS) 分析确定了腐蚀产物中Cr、V和Cl含量与分布情况，用X射线衍射 (XRD) 和Rietveld分析确定了腐蚀产物各锈层相的相对含量。结果表明：当腐蚀时间达到288 h时，钢表面逐渐形成内层 (30~50 μm) 和外层 (100~180 μm) 的两层结构锈层。其中外层主要是由γ-FeOOH组成，很容易剥落；而内层包含α-FeOOH和Fe₃O₄，结构较致密，与基体结合比较牢固。Cr和V在内层锈层中明显富集，而没有Cl^-，说明在内层锈层区域Cl^-侵入受到阻止；而外层锈层中Cr和V基本没有富集，且含有一定量的Cl^-；通过XRD分析腐蚀的不同阶段和不同部位的锈层成分图谱及相对含量关系，分析了γ-FeOOH形成和γ-FeOOH转化为α-FeOOH的过程。基于上述分析构建了不同相的转化模型。     

烟道气氨法脱硫液对Q235碳钢腐蚀研究

采用静态挂片、极化曲线和长期点蚀实验，研究了氨法脱硫浆液中F^-和Cl^-以及 (NH₄)₂SO₄对Q235碳钢腐蚀的影响。结果表明，Q235碳钢在含卤硫铵溶液中的均匀腐蚀速率随F^-浓度和Cl^-浓度增大均呈现先降低后增高的趋势，随着 (NH₄)₂SO₄质量分数增加，均匀腐蚀速率降低；随着F^-浓度的增大，自腐蚀倾向增加；随着Cl^-浓度以及 (NH₄)₂SO₄质量分数的增大，自腐蚀倾向均降低；Q235碳钢在氨法脱硫模拟浆液中点蚀较严重，需采取重防腐措施。